Light source control apparatus, light source control method, and projector

ABSTRACT

A light source control apparatus includes a controller, and a plurality of drivers. The controller transmits an instruction value for adjusting a light amount of at least one light emitting unit. Each of the plurality of drivers obtains the transmitted instruction value, and determines, by using a function of a driving value for driving the light emitting unit and the light amount, the function being each set for the light emitting unit, the driving value of the light emitting unit each on the basis of the instruction value.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/565,989, filed Oct. 12, 2017, which is aNational Stage Entry of PCT/JP2016/001746, filed Mar. 25, 2016, andclaims the benefit of priority from prior Japanese Patent Application2015-154780 filed in the Japan Patent Office on Aug. 5, 2015, andJapanese Patent Application 2015-092552 filed in the Japan Patent Officeon Apr. 30, 2015, the entire contents of which are hereby incorporatedby reference.

TECHNICAL FIELD

The present technology relates to a projector, a light source controlapparatus for controlling a light source of the projector, and a lightsource control method.

BACKGROUND ART

Patent Literature 1 discloses a driver circuit that drives lightemitting diodes. The driver circuit includes: light emitting units, eachgroup of the light emitting units including six light emitting diodesconnected in series; a plurality of drivers, each of the plurality ofdrivers driving a plurality of groups, each of the plurality of groupsincluding a plurality of light emitting units; and one driver control ICchip that controls the plurality of drivers. Specifically, the drivercontrol IC chip outputs target current value signals for controlling thelight emitting units to emit light and adjustment instruction signals toto the respective drivers. When each driver receives an adjustmentinstruction, each driver adjusts the current by using a voltageadjusting circuit such that the current flowing in the light emittingunits reaches the target current value. Because the drivers executeadjustment in a temporally overlapping manner, the time until all therespective drivers finish adjustment is shortened (for example, seePatent Literature 1, specification, paragraphs, and, and FIGS. 1, 3, and4).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Application Laid-open No.2013-175676

DISCLOSURE OF INVENTION Technical Problem

In the driver circuit of Patent Literature 1, the plurality of driversdrive the plurality of light emitting units, respectively. According tothis mode, the driving currents and the light amounts corresponding tothe driving currents may be different sometimes depending on individualdifferences of the light emitting units. In this case, in order toadjust the light amounts of the light emitting units to make themuniform, it is necessary for a controller unit to generate differentinstruction values for the respective drivers, and it is thus difficultto adjust the light amount fast. Further, for example, there is known amethod of mechanically adjusting a light amount by using an iris.However, there is a limitation to adjust a light amount fast by using amechanical means.

In view of the above-mentioned circumstances, it is an object of thepresent technology to provide a light source control apparatus capableof adjusting a light amount fast, a light source control method, and aprojector using them.

Solution to Problem

To attain the above-mentioned object, according to the presenttechnology, a light source control apparatus includes a controller, anda plurality of drivers.

The controller is configured to transmit an instruction value foradjusting a light amount of at least one light emitting unit.

Each of the plurality of drivers is configured to obtain the transmittedinstruction value, and to determine, by using a function of a drivingvalue for driving the light emitting unit and the light amount, thefunction being each set for the light emitting unit, the driving valueof the light emitting unit each on the basis of the instruction value.

The controller transmits the instruction value, and thereby each of theplurality of drivers determines a driving value by using a predeterminedfunction. Therefore it is possible to adjust the light amount fast.

Each driver of the plurality of drivers may be configured to use, as thefunction, a function approximated by a straight line.

Therefore it is possible to reduce the calculation amount of thedrivers, and the light amount may be adjusted faster.

Each driver of the plurality of drivers may be configured to use, as thefunction, a plurality of functions set corresponding to a plurality ofdriving regions, respectively.

Therefore the light amount is adjusted more accurately.

Each driver of the plurality of drivers may be configured to use, as thefunction approximated by a straight line, functions approximated bystraight lines in a plurality of linear regions set corresponding to aplurality of driving regions, respectively.

Therefore the light amount is adjusted more accurately, and, inaddition, the calculation amount of the drivers may be reduced as muchas possible.

Each driver of the plurality of drivers may be configured to use thefunction with known parameters, the known parameters including aninclination of the straight line, a reference light amount, and areference driving value corresponding to the reference light amount.

Each driver of the plurality of drivers may be configured to obtain fromthe controller or prestore a calculated value based on the inclinationof the straight line and the reference light amount out of the knownparameters.

Therefore the calculation amount at the time of adjusting the lightamount is reduced, and the light amount may be adjusted faster. Toprestore means to prestore before adjusting the light amount.

The controller may be configured to update the function on the basis ofa predetermined condition.

Therefore, even if the light emitting units deteriorate over time orover years, the light amount may be adjusted accurately.

The plurality of drivers may include a plurality of first wavelengthband light-emitting drivers, and a plurality of second wavelength bandlight-emitting drivers.

Each of the plurality of first wavelength band light-emitting drivers isconfigured to drive a plurality of light emitting units that emit lighthaving a first wavelength band out of the at least one light emittingunit.

Each of the plurality of second wavelength band light-emitting driversis configured to drive a plurality of light emitting units that emitlight having a second wavelength band different from the firstwavelength band out of the at least one light emitting unit.

Further, the controller may be configured to transmit a firstinstruction value to each of the plurality of first wavelength bandlight-emitting drivers, and to transmit a second instruction value toeach of the plurality of second wavelength band light-emitting drivers.

Therefore, even in a mode in which the light emitting units emit lightof two or more colors, it is possible to adjust the light amount fast.

The plurality of drivers may include a first driver and a second driver.

The first driver is configured to generate a voltage between a referencepotential of a reference line and a potential of a first line higherthan the reference potential, and to drive the first light emitting unitconnected between the reference line and the first line, the firstdriver being connectable to the reference line and the first line.

The second driver is configured to generate a voltage between thereference potential and a potential of a second line lower than thereference potential, and to drive the second light emitting unitconnected between the reference line and the second line, the seconddriver being connectable to the reference line and the second line.

Since the second driver generates a voltage at a potential lower thanthe reference potential, the sum of the current flowing into acontroller board including the controller, the first driver, and thesecond driver via the reference line is reduced. In other words, sincethe current flowing into the controller board via the reference line isreduced, generation of a potential difference based on the referenceline pattern of the controller board may be reduced. Thereforegeneration of a common-mode noise may be reduced. In this specification,“connection” means electric connection.

Each of the first driver and the second driver may be configured to usea potential of 0 volts as the reference potential.

Since the reference potential is 0 V, the design of the circuit of eachdriver may be simple.

A constant potential may be set as the reference potential, and thesecond driver may be configured to adjust a potential lower than thereference potential to adjust the driving value.

Since the potential lower than the reference potential is adjusted,troubles of the second drivers and the other circuits are reduced andsafety is increased, which are advantageous effects.

The first driver may be configured to adjust a potential higher than thereference potential to adjust the driving value.

The light source control apparatus may further include a switcher unitthat switches connection targets of the first light emitting unit suchthat an anode of the first light emitting unit is connected to thereference line and a cathode of the first light emitting unit isconnected to the second line.

As a result, even if some of the light emitting units are in trouble, itis easy to control the light source unit, and generation of illuminanceunevenness may be prevented.

Similarly, the light source control apparatus may further include aswitcher unit that switches connection targets of the second lightemitting unit such that a cathode of the second light emitting unit isconnected to the reference line and an anode of the second lightemitting unit is connected to the first line.

The light source control apparatus may further include a resistorelement provided on at least one of a line connected to the controllerand a line connected to the plurality of drivers out of the referenceline.

As a result, the return current is converted into thermal energy by theresistor element, and therefore the value of the return current flowinginto the controller and the plurality of drivers may be reduced.

Each driver of the plurality of drivers may be configured to use, as thefunction, a function of an average light amount, the average lightamount being obtained by dividing a total light amount of the pluralityof light emitting units corresponding to driving values by the number ofthe light emitting units.

Each driver of the plurality of drivers may be configured to use switchstart timing of the driving value based on the instruction value, theswitch start timings of the plurality of drivers being different fromeach other.

Delay time may be set for the switch start timing of the driving valueof at least one of the respective drivers.

Each driver of the plurality of drivers may be configured to selectivelyuse the plurality of different switch start timings depending on achange amount of the driving values before and after switching thedriving value.

According to the present technology, a light source control methodincludes transmitting, by a controller, an instruction value foradjusting a light amount of at least one light emitting unit.

The method further includes obtaining, by each of a plurality ofdrivers, the transmitted instruction value.

The method further includes determining, by each of the plurality ofdrivers, by using a function of a driving value for driving the lightemitting unit and the light amount, the function being each set for thelight emitting unit, the driving value of the light emitting unit eachon the basis of the instruction value.

According to another embodiment of the present technology, a lightsource control apparatus includes the first driver, the second driver,and a controller unit.

The controller unit is connectable to the reference line, the firstdriver, and the second driver, the controller unit being configured tocontrol the first driver and the second driver.

Since the second driver generates a voltage at a potential lower thanthe reference potential, the sum of the current flowing into thecontroller unit, the first driver, and the second driver via thereference line is reduced. In other words, since the current flowinginto the controller unit via the reference line is reduced, generationof a potential difference based on the reference line pattern of thecontroller unit may be reduced. Therefore generation of a common-modenoise may be reduced.

According to an embodiment of the present technology, a driver unitincludes the first driver, and the second driver.

According to the present technology, a light source unit includes afirst light emitting unit, and a second light emitting unit.

The first light emitting unit is connected between a reference line anda first line, the first light emitting unit being driven by a currentgenerated by a voltage between a reference potential of the referenceline and a potential of the first line higher than the referencepotential.

The second light emitting unit is connected between the reference lineand a second line, the second light emitting unit being driven by acurrent generated by a voltage between the reference potential of thereference line and a potential of the second line lower than thereference potential.

According to the present technology, a projector includes a plurality oflight emitting units, a light modulation device that modulates lightfrom the plurality of light emitting units, a projection optical systemthat projects modulated light obtained by modulating the light by thelight modulation device, and the light source control apparatus. In theprojector, the plurality of light emitting units may include a firstlight emitting unit connected between a reference line and a first line,and a second light emitting unit connected between the reference lineand a second line. The plurality of drivers may include the first driverand the first driver.

According to another embodiment of the present technology, a projectorincludes the plurality of light emitting units, the light modulationdevice, the projection optical system, the driver unit, and thecontroller unit.

Advantageous Effects of Invention

As described above, according to the present technology, it is possibleto adjust the light amount of the light emitting units fast.

Note that the above-mentioned effects are not necessarily limitations,but any effect described in the present disclosure may be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing a configuration of a light sourcecontrol apparatus according to an embodiment of the present technology.

FIG. 2 is a graph showing a relation between a driving current, i.e., adriving value of the light emitting unit, and a light amount.

FIG. 3 is a graph showing the relation between the driving current andthe light amount of an embodiment, in which a function is approximatedby one straight line in the driving region of the oscillation thresholdcurrent or more.

FIG. 4 is a flowchart showing the operation of the light source controlapparatus, which has the relation between the driving current and thelight amount of FIG. 3.

FIG. 5 is a graph showing the relation between the driving current andthe light amount of an embodiment, in which a function is approximatedby two straight lines in the driving region of the oscillation thresholdcurrent or more.

FIG. 6 is a flowchart showing the operation of the light source controlapparatus having the relation between the driving current and the lightamount of FIG. 4.

FIG. 7 is a block diagram showing a light source control apparatusaccording to another embodiment of the present technology.

FIG. 8 shows an example of the structure of an optical system of aprojector including the light source control apparatus of FIG. 7.

FIG. 9 shows a configuration of a light source and a light sourcecontrol apparatus for illustrating another problem, and is a diagramshowing a comparative example of the present technology.

FIG. 10 shows configurations of a light source unit and a light sourcecontrol apparatus for controlling the light source unit according to anembodiment for solving the above-mentioned other problem.

FIG. 11 shows configurations of a light source unit and a light sourcecontrol apparatus for controlling the light source unit according to anembodiment different from the embodiment of FIG. 10.

FIG. 12 is a graph showing the relation between the driving current andthe light amount of Embodiment 3.

FIG. 13A is a graph showing the relation between the driving current andthe total light amount. FIG. 13B is a graph showing the relation betweenthe driving current and the average light amount.

FIG. 14A shows an example in which the driving current is changed(decreased by predetermined current value) to adjust the light amountwhere no delay time is set (comparative example). FIG. 14B shows, inthis embodiment, an example in which the settlement completed timing isapproximately at the same time where the delay time is set.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present technology will be describedwith reference to the drawings.

1. Configuration of Light Source Control Apparatus

FIG. 1 is a block diagram showing a configuration of a light sourcecontrol apparatus according to an embodiment of the present technology.The light source control apparatus 101 is, typically, an apparatus thatdrives a light source of a projector including a light modulation devicesuch as a liquid crystal device. In this embodiment, an example of alight source control apparatus that receives an image signal (videosignal) from the projector and controls light emission on the basisthereof will be described.

The light source control apparatus 101 includes the video signalprocessor 15, the controller 20, and the plurality of drivers 30. Thelight source (light source unit) 50 including the plurality of lightemitting units 40 is electrically connected to the plurality of drivers30.

The video signal processor 15 is, for example, a chip for processing avideo signal, and processes a video signal input from, for example, anexternal apparatus (for example, PC) in various ways. Further, the videosignal processor 15 is configured to transmit, for example, luminancedata to the controller 20 as part of the video data.

The controller 20 includes, for example, the main controller 22 and theinterface unit 24.

The main controller 22 mainly includes a CPU (Central Processing Unit)or an MPU (Micro Processing Unit), and includes a RAM (Random AccessMemory), a ROM (Read Only Memory), and the like. The main controller 22is configured to obtain the luminance data and the like output from thevideo signal processor 15.

Especially, the main controller 22 has a function of controlling thelight amounts of the plurality of light emitting units 40 on the basisof the obtained luminance data by using a predetermined algorithm suchthat all the plurality of light emitting units 40 generate light havingsubstantially the same brightness. Typically, the controller 20 isconfigured to control driving of the respective drivers 30 such that allthe plurality of light emitting units 40 have substantially the sameluminance for each one frame (or maybe a plurality of frames) of a videosignal.

The predetermined algorithm is, for example, an algorithm for causingthe light emitting units 40 to emit light having luminance having agrade of a predetermined number of bits depending on the total luminanceof each frame. According to such an algorithm, for example, where anentire display is black, in order to minimize light that leaks from aliquid crystal device, relatively small luminance of all the pluralityof light emitting units 40 is set. Note that, according to thisalgorithm, where the almost entire area of the display is black and thedisplay partially has a relatively bright area, the luminance of all theplurality of light emitting units 40 is uniform and corresponds to theluminance of the relatively bright area. In other words, the luminanceof all the plurality of light emitting units 40 is adjusted such thatthe highest luminance value may be reproduced out of the luminancevalues of all the pixels of image data input in a projector. In thismanner, by transmitting an instruction value for adjusting the lightamount of the light emitting units on the basis of input image data, itis possible to reduce the light amount of the light emitting units wherethe entire display is dim. Therefore it is possible to reduce powerconsumption of the light emitting units 40 and extend the lifetime ofthe light emitting units 40. Further, the amount of light blocked by aliquid crystal device may be reduced, and the lifetime of the liquidcrystal device may thus be longer.

The interface unit 24 includes a control board that receives aninstruction value for adjusting a light amount output from the maincontroller 22 and broadcasts the instruction value to the respectivedrivers 30. As a standard of transferring from the main controller 22 tothe interface unit 24, for example, UART (Universal AsynchronousReceiver Transmitter) is used, which realizes the system inexpensively.As a matter of course, another standard may be employed.

In this embodiment, the main controller 22 and the interface unit 24 areindependent chips, but one chip may include the main controller 22 andthe interface unit 24.

The driver 30 has a function of driving the light emitting unit 40. Eachlight emitting unit 40 is connected to each driver 30. The drivers 30are connected to the interface unit 24 in parallel. For example, four totwenty drivers 30 and four to twenty light emitting units 40 areprovided, but not limited to this range. One light emitting unit 40includes the plurality of light emitting devices 42 connected in series.As the light emitting device 42, for example, an LD (Laser Diode) isused.

As a standard of the interface between the interface unit 24 and eachdriver 30, for example, I2C or SPI (Serial Peripheral Interface) isused. I2C has a function of the general call address, and is capable ofselecting all the slaves where 0 is set for the slave address. As aresult, if is possible to broadcast notification from the interface unit24 to the respective drivers 30.

In SPI, an SS (Slave Select) signal is used. Where lines are connectedto slaves one by one, the number of lines is large, the area for thenumber of lines is required for the board, and the ports for the numberof lines are required for the master. For example, it is possible tobroadcast a notification by defining an instruction for transmitting theID number (corresponding to slave address) of a driver board includingthe drivers 30 and by selecting all the slaves.

2. Principle of Light Emitting Control by Light Source Control Apparatus

2. 1) Relation Between Driving Value and Light Amount of Light EmittingUnit

FIG. 2 is a graph showing a relation between a driving current ,i.e., adriving value of the light emitting unit 40, and a light amount. Here,as described above, a principle of light emitting control in order thatall the plurality of light emitting units 40 may obtain substantiallythe same and uniform luminance will be described.

Each light emitting unit 40 has a relation shown in FIG. 2, and therelations (graphs) of the respective light emitting units 40 havesubstantially the same form.

However, the relations of the light emitting units 40 are slightlydifferent from each other. As a matter of course, the relations of atleast two light emitting units 40 out of all the light emitting units 40may have no difference, and may have the relation between a drivingcurrent and a light amount having the same form.

With reference to FIG. 2, P0 is a light amount corresponding to theoscillation threshold current I0 of the light emitting devices 42 of thelight emitting unit 40. The oscillation threshold current I0 is,specifically, a current value for generating the minimum light amount.Pc is a reference light amount and is the maximum light amount in thisembodiment. Ic is a driving current as a reference driving value(reference driving current) for obtaining the reference light amount.

Py is a light amount corresponding to an arbitrary driving current Iy.The following Formula 0.1 using the function f shows the relation.Py=f(Iy)  Formula 0.1The following Formula 0.2 shows Formula 0.1 by using the inversefunction f⁻¹.Iy=f ⁻¹(Py)  Formula 0.2

The following Formula 0.3 shows the change rate from the maximum lightamount, i.e., the rate y (where 0≤y≤1) of the target light amount withrespect to the maximum light amount. Therefore Formula 0.4 is thusobtained.y=Py/Pc  Formula 0.3Py=y*Pc  Formula 0.4

The following Formula 0.5 is obtained on the basis of Formula 0.2 andFormula 0.4.Iy=f ⁻¹(y*Pc)  Formula 0.5

For example, each driver 30 prestores the function (inverse function)f⁻¹ and Pc. The controller 20 broadcasts the instruction value y to therespective drivers 30, and the respective drivers 30 may thus calculateIy individually by using Formula 0.5. In other words, each driver 30 maydetermine each driving current Iy on the basis of the instruction valuey by using the function f⁻¹. As described above, since f³¹ ¹ of thelight emitting units 40 may be slightly different from each other, thedriving currents Iy of the respective drivers 30 may be different fromeach other even if the same instruction value y is used.

For example, each driver 30 may store, instead of f⁻¹ and Pc, a drivingcurrent data value defined by Formula 0.5 and the corresponding lightamount data value in a look-up table style. Each driver 30 may have avolatile or non-volatile memory. For example, where each memory is avolatile memory, the controller 20 may prestore data of the functionsf⁻¹ or data of the look-up tables. Further, at a time when the lightsource control apparatus 101 is powered on or at a predetermined timeafter that, the controller 20 may supply the functions f⁻¹ or thelook-up tables to the respective drivers 30.

For example, where each driver 30 has a non-volatile memory, once thecontroller 20 transmits the data of the functions f⁻¹ or the data of thelook-up tables to the drivers 30 and the respective drivers 30 obtainthe data, each non-volatile memory may store the data after that.Alternatively, each non-volatile memory may prestore factory-configureddata.

2. 2) Embodiment 1 (Example 1 of Specific Function)

Hereinafter, as a specific embodiment of the above-mentioned function for f⁻¹, an example, in which the function is approximated by onestraight line in the driving region of the oscillation threshold currentI0 or more, will be described. FIG. 3 is a graph showing the relationbetween the driving current and the light amount of this embodiment. Inthe graph of the present Embodiment 1, the function is approximated by astraight line in the driving region from the oscillation thresholdcurrent I0 to the reference driving current Ic corresponding to themaximum light amount Pc. As shown in the following Formula 1.1, k1 showsthe inclination (Pb−Pa)/(Ib−Ia) of the straight line of the graph.k1=(Pb−Pa)/(Ib−Ia)  Formula 1.1

Formula 1.1 means Formula 1.2. In other words, as shown in Formula 1.3,Iy is represented by a function of Py.Py−Pc=k1(Iy−Ic)  Formula 1.2Iy=f ⁻¹(Py)  Formula 1.3

Specifically, the following Formula 1.4 based on Formula 1.2 shows Iy.Iy=(Py−Pc)/k1+Ic  Formula 1.4Where y=Py/Pc and 0≤y≤1, the following Formula 1.5 is derived on thebases of Formula 1.4.Iy=Pc(y−1)/k1+Ic  Formula 1.5Where ζ=Pc/k1, Formula 1.5 is represented by the following Formula 1.6.Iy=(y−1)ζ+Ic  Formula 1.6

Each driver 30 stores k1, Pc, and Ic as known parameters. Instead of k1and Pc, the value ζ calculated on the basis of k1 and Pc may be stored.In order to change the light amount into Py, the interface unit 24 ofthe controller 20 broadcasts, for example, y−1 as an instruction valueto the drivers 30, and each driver 30 may thus calculate the drivingcurrent Iy by using Formula 1.6.

FIG. 4 is a flowchart showing the operation of the light source controlapparatus 101 of the present Embodiment 1.

When the light source control apparatus 101 is powered on, thecontroller 20 transmits, for example, as default, the above-mentionedknown parameters Ic and ζ, which are predetermined for each driver 30,to each driver 30 (Step 101). Each driver 30 obtains Ic and ζ, andstores them in the memory. As described above, each driver 30 mayprestore Ic and ζ in a non-volatile memory.

Then the controller 20 transmits a drive start command for driving thelight emitting units 40, the current Ic being the target drivingcurrent, to the respective drivers 30 (Step 102). The drive startcommand is also broadcasted and transmitted, typically. Next, when thecontroller 20 receives an instruction for adjusting the light amount(here, adjusting dimming) from the video signal processor 15, forexample, the controller 20 broadcasts the same instruction value y−1 tothe respective drivers 30 (Step 103). The instruction value y−1 is avalue calculated on the basis of the change rate y from the maximumlight amount Pc.

Each driver 30 determines, as the target driving current, the current Iyby using Formula 1.6 including Ic and ζ stored in Step 101 and on thebasis of the obtained instruction value y−1, and drives the lightemitting unit 40 at the driving current Iy (Step 104).

As described above, the controller 20 broadcasts the instruction valuey−1, and each driver 30 thus calculates the driving current Iy by usingFormula 1.6. In other words, it is not necessary for the controller 20to transmit driving current values, which may be different for eachlight emitting unit 40 (each driver 30), to the respective drivers 30.Therefore the light amount may be adjusted faster.

Especially, if the controller 20 transmits different instruction valuesto the respective drivers 30 (in order to make the light amounts of thelight emitting units 40 different from each other uniform), thecontroller 20 does not have enough time to transmit the differentinstruction values for the timing of each one frame. According to thepresent Embodiment 1, it is only necessary for the controller 20 tobroadcast the common instruction value, and the light amounts of thelight emitting units 40 may be adjusted for each one frame, for example.

As a matter of course, the controller 20 may transmit y instead of y−1asan instruction value. In this case, each driver 30 calculates y−1.However, since the value y−1 is common to the respective drivers 30, thelight amount may be adjusted faster where the controller 20 calculatesy−1.

Alternatively, the controller 20 may not prestore ζ as described above,but may calculate Pc/k1 every time the controller 20 adjusts the lightamount. However, Pc/k1 is known. By previously executing calculationsuch as division as described in this embodiment, the calculation amountat the time of adjusting the light amount is reduced, and the lightamount may be adjusted faster.

2. 3) Embodiment 2 (Example 2 of Specific Function)

FIG. 5 shows functions according to another embodiment different fromthe above-mentioned Embodiment 1. In this embodiment, descriptionsimilar to the description made in the above-mentioned Embodiment 1 willbe simplified or omitted, and different points will be described mainly.

In the present Embodiment 2, as shown in FIG. 5, the functions areapproximated in a plurality of linear regions corresponding to aplurality of driving regions from the oscillation threshold current I0to the reference driving current Ic being the reference driving value.In other words, a plurality of functions are defined in the drivingregions of the oscillation threshold current I0 or more. Specifically,the functions are set for two linear regions divisionally.

For the purpose of illustration, the region from the driving current Ibto the reference driving current Ic will be referred to as the firstdriving region, and the region from the oscillation threshold current I0to the driving current Ib will be referred to as the second drivingregion. The inclination k1 of the straight line in the first drivingregion and the inclination k2 of the straight line in the second drivingregion are represented by the following Formula 2.1 and Formula 2.2,respectively.k1=(Pc−Pb)/(Ic−Ib)  Formula 2.1k2=(Pb−Pa)/(Ib−Ia)  Formula 2.2

In the first driving region (Pb<Py), similar to the above-mentionedFormula 1.6, the following Formula 2.3 is derived by using theinclination k1.Iy=(y−1)ζ1+Ic  Formula 2.3Where ζ1=Pc/k1 and y=Py/Pc

In the second driving region (P0<Py≤Pb), the following Formula 2.4 isderived by using the inclination k2.Py=Pb+k2(Iy−Ib)  Formula 2.4

The following Formula 2.5 is obtained by deforming Formula 2.4 wherey=Py/Pc.Iy=y*Pc/k2−Pb/k2+Ib  Formula 2.5Where ζ2=Pc/k2 and ζ3=Pb/k2, Formula 2.5 is represented by the followingFormula 2.6.Iy=ζ2y−ζ3+Ib  Formula 2.6

As described above, each driver 30 is configured to calculate thedriving current Iy by using Formula 2.3 in the first driving region andby using Formula 2.6 in the second driving region. Each driver 30 storesk1, k2, Pc, Ic, Pb, and Ib as known parameters. Each driver 30 maystore, instead of k1, the value ζ1 calculated on the basis of k1 and Pc,and may store, instead of k2, the value ζ2 calculated on the basis of k2and Pc. Alternatively, each driver 30 may store, instead of k2, thevalue ζ3 calculated on the basis of k2 and Pb.

In order to change the light amount into Py corresponding to the firstdriving region, the controller 20 broadcasts, for example, y (or maybey−1) as the instruction value to the drivers 30. Therefore each driver30 is capable of calculating the driving current Iy by using Formula 2.3or Formula 2.6.

FIG. 6 is a flowchart showing the operation of the light source controlapparatus of the present Embodiment 2.

When the light source control apparatus 101 is powered on, thecontroller 20 transmits, for example, as default, the above-mentionedknown parameters Ic, Ib, ζ1, ζ2, and ζ3, which are predetermined foreach driver 30, to each driver 30 (Step 201). Each driver 30 obtains Ic,Ib, ζ1, ζ2, and ζ3, and stores them in the memory. As described above,each driver 30 may prestore Ic, Ib, ζ1, ζ2, and ζ3 in a non-volatilememory.

The controller 20 transmits a drive start command for driving the lightemitting units 40, the current Ic being the target driving current, tothe respective drivers 30 (Step 202).

When the controller 20 receives an instruction for adjusting the lightamount (here, adjusting dimming) from the video signal processor 15, forexample, the controller 20 broadcasts the same instruction value y tothe respective drivers 30 (Step 203).

Each driver 30 executes determining process of the instruction value y.In other words, each driver 30 determines whether the light amount Pyexceeds Pb or not (Step 204). In Step 204, each driver 30 may prestorethe rate y1 of Pb with respect to Pc, i.e., y1=Pb/Pc (for example, mayfurther obtain Pb from the controller 20 in Step 201, and may calculateand store Pb/Pc=y1), and may determine whether y1<y.

Where each driver 30 determines that Pb<Py (y1<y), each driver 30determines, as the target driving current, the current Iy by usingFormula 2.3 and on the basis of the instruction value y, and drives thelight emitting unit 40 at the driving current Iy (Step 205). Meanwhile,where each driver 30 does not determine that Pb<Py (y1<y), each driver30 determines, as the target driving current, the current Iy by usingFormula 2.6 and on the basis of the instruction value y, and drives thelight emitting unit 40 at the driving current Iy (Step 206).

As described above, according to the present Embodiment 2, the relationbetween the driving current and the light amount is defined for each ofa plurality of divided driving regions. Therefore, although thecalculation amount is larger than that of Embodiment 1, the light amountis adjusted more accurately.

2. 4)

The above-mentioned Embodiments 1 and 2 also have the following effects.Since the respective drivers 30 execute calculation in parallel in thisembodiment, the calculation execution time period of this embodiment isshorter than that of a mode, in which a controller such as a CPU and anMPU calculates and transmits current target values set for respectivedrivers.

Further, since the calculation processing amount of the main controller22 is reduced, the load applied to the main controller 22 is reduced andthe main controller 22 may execute other necessary processing faster.

3. Light Source Control Apparatus of Another Embodiment

FIG. 7 is a block diagram showing a light source control apparatusaccording to another embodiment of the present technology. The lightsource control apparatus 102 includes the three light sources 50R, 50G,and 50B that emit lights of three different colors in place of the lightsource of the light source control apparatus 101 of FIG. 1. In otherwords, the light source control apparatus 102 includes the light sources50R, 50G, and 50B that emit lights having a plurality of wavelengthbands.

The light source 50R includes the plurality of light emitting units 40that emit light having the red wavelength band, for example. The lightemission G includes the plurality of light emitting units 40 that emitlight having the green wavelength band, for example. The light source50B includes the plurality of light emitting units 40 that emit lighthaving the blue wavelength band, for example. In other words, the lightsources 50R, 50G, and 50B generate white light. Similar to the modeshown in FIG. 1, the light emitting unit 40 includes the plurality oflight emitting devices 42 connected in series.

The controller 20 obtains luminance data of video signals correspondingto the three light sources 50R, 50G, and 50B from the video signalprocessor 15. The controller 20 causes, on the basis of the luminancedata, each of the light sources 50R, 50G, and 50B to emit light at thebrightness (luminance) of all the light emitting units 40 of each lightsource 50 for one frame or a plurality of frames. The controller 20 isconfigured to broadcast instruction values basically different for eachlight source 50 (or maybe same instruction value) to all the lightsources 50 at the same timing all together. Alternatively, thetransmission timing may be slightly different for each of the differentlight sources 50 as long as video display is not affected (for example,time difference shorter enough than the time of one frame).

Further, each drivers 30 determines the driving current by using theabove-mentioned function and on the basis of the instruction value ofeach light source, and causes each of the light sources 50R, 50G, and50B to emit light at the driving current.

As described above, the controller 20 broadcasts the instruction values(at least including first instruction value and second instructionvalue) to the drivers 30 (at least including plurality of firstwavelength band light-emitting drivers and plurality of secondwavelength band light-emitting drivers), the drivers 30 being providedfor the light sources 50 that generate light having a plurality ofwavelength bands (i.e., at least including first wavelength band andsecond wavelength band). Further, since each driver 30 determines thedriving current by using the function, the light amount may be adjustedfaster where the three light sources 50R, 50G, and 50B are used.

4. Projector

FIG. 8 shows an example of the structure of an optical system of aprojector including the light source control apparatus 102 of FIG. 7,for example. The projector 500 includes the light source apparatus 100capable of emitting white light, the image generating unit 200 thatgenerates an image on the basis of the light source apparatus 100, andthe projection unit (projection optical system) 400 that projects thegenerated image on a screen or the like (not shown).

The light source apparatus 100 combines the red laser light R having thered wavelength band, the green laser light G having the green wavelengthband, and the blue laser light B having the blue wavelength band, andemits the white light W. The light source apparatus 100 is an apparatusincluding the light source control apparatus 102 of FIG. 7, for example.

The image generating unit 200 includes the light modulation devices 210that generate an image on the basis of emitted light, and theillumination optical system 220 that irradiates the light modulationdevices 210 with white light from the light source apparatus 100. Theillumination optical system 220 includes the dichroic mirrors 260 and270, the mirrors 280, 290, and 300, the relay lenses 310 and 320, thefield lenses 330R, 330G, and 330B, the liquid crystal devices 210R,210G, and 210B as the light modulation devices 210, for example, and thedichroic prism 340.

Each of the dichroic mirrors 260 and 270 has a property of selectivelyreflecting light having color of a predetermined wavelength band andtransmitting light having the other wavelength band. For example, thedichroic mirror 260 selectively reflects the green laser light G and theblue laser light B. The dichroic mirror 270 selectively reflects thegreen laser light G out of the green laser light G and the blue laserlight B reflected by the dichroic mirror 260. The dichroic mirror 270transmits the remaining blue laser light B. As a result, light emittedfrom the light source apparatus 100 is separated into a plurality oflaser lights having different colors. Note that the structure forseparating light into a plurality of laser lights, the used devices, andthe like are not limited to the above.

The separated red laser light R is reflected by the mirror 280, passesthrough the field lens 330R and is thus parallelized, and enters theliquid crystal device 210R. The green laser light G passes through thefield lens 330G and is thus parallelized, and enters the liquid crystaldevice 210G. The blue laser light B passes through the relay lens 310,is reflected by the mirror 290, then passes through the relay lens 320,and is reflected by the mirror 300. The blue laser light B, which isreflected by the mirror 300, passes through the field lens 330B and isthus parallelized, and enters the liquid crystal device 210B.

The liquid crystal devices 210R, 210G, and 210B are electricallyconnected to a signal source (for example, PC, etc.) (not shown) thatsupplies image signals including image information. Each of the liquidcrystal devices 210R, 210G, and 210B modulates entered light for eachpixel on the basis of the supplied image signal of each color, andgenerates each of a red image, a green image, and a blue image. Themodulated laser lights (formed images) of the respective colors enterthe dichroic prism 340 and are combined. The dichroic prism 340superimposes the lights of the respective colors entered in the threedirections on one another to combine the lights, and emits the combinedlight toward the projection unit 400.

The projection unit 400 projects the image generated by the lightmodulation devices 210. The projection unit 400 includes the pluralityof lenses 410 and the like, and irradiates a screen or the like (notshown) with the light combined by the dichroic prism 340. As a result, afull-color image is displayed.

5. Other Various Embodiments

The present technology is not limited to the above-mentionedembodiments, but other various embodiments may be realized.

For example, the controller 20 may be configured to update a function orparameters of the function on the basis of predetermined conditions.Specifically, predetermined conditions include elapse of predetermineddays after power-on, a case where the latest known parameters aredifferent from (the known parameters of) the function factory-stored inthe light source control apparatus as default, and the like. In thelatter case, for example, the light source control apparatus may includea luminance sensor or the like, and the controller 20 may be configuredto inspect and record the driving current and the light emitting amountof the light emitting units 40 periodically, occasionally, when anoperation is input by a user, or the like. As a result, even if thelight emitting units 40 deteriorate over time or over years, the lightamount may be adjusted accurately.

An LED (Light Emitting Diode) may be used as a device being each lightemitting unit 40 of the light source 50 in place of an LD.

In the above-mentioned embodiments, the reference light amount is themaximum light amount. Not limited to this, it may be an arbitrary lightamount.

A liquid crystal device is used as the light modulation device.Alternatively, a DMD (Digital Micro-mirror Device) may be used.

A projector that projects a 3D video may be realized where the lightsource control apparatus 102 of FIG. 7 further includes the three RGBlight sources 50R, 50G, and 50B of another system. In this case, thelight source control apparatus 102 is designed such that six parallellines are connected to the interface unit 24 (see FIG. 7).

In the above-mentioned embodiments, the controller is configured tobroadcast the instruction value to the respective drivers. However, thecontroller is not necessarily to “broadcast” the instruction value tothe respective drivers, but may be configured to transmit theinstruction value to at least two drivers at different timing.

In the above-mentioned embodiments, one light emitting unit 40 includesthe plurality of light emitting devices 42, but may include a singlelight emitting device 42. The above-mentioned embodiments of the lightsource control apparatus may be combined with the embodiments of a lightsource control apparatus and a light source unit described below.Further, the above-mentioned projector may include a light sourcecontrol apparatus and a light source unit of the embodiment describedbelow.

At least two characteristic parts out of the characteristic parts of theabove-mentioned embodiments may be combined. The same applies toembodiments described below.

6. Problem Resulting from Return Current of Light Source

By the way, each light emitting unit of a light source has a relativelylarge return current. When such a large current flows into a referenceline (typically, ground line) of a controller board of an electronicapparatus, the following problem may occur. In short, when a largecurrent flows into the ground line, a potential difference is generatedon the basis of a resistance value defined by the wiring pattern, and acommon-mode noise is generated as a result.

It is another object of the present disclosure to provide a technologycapable of reducing generation of a potential difference generated dueto a wiring pattern of a reference line.

FIG. 9 shows a configuration of a light source and a light sourcecontrol apparatus for illustrating the above-mentioned problemspecifically, and is a diagram showing a comparative example of thepresent technology. An apparatus of FIG. 9 includes the power sourceunit 60, the controller unit (for example, controller board) 120, thedriver unit 150, and the light source (light source unit) 50. Note that,in the above-mentioned embodiments of FIG. 1 and the like, the powersource unit 60 is not shown and description thereof is omitted.

The controller unit 120 transmits control signals to the plurality ofdrivers 30 of the driver unit 150, and controls the respective driver 30to drive. The controller unit 120 includes a board unit including “thecontroller 20” (see FIG. 1) of the above-mentioned embodiment, forexample. In this case, the controller unit 120 may include the interfaceunit 24 and the video signal processor 15. Alternatively, the controllerunit 120 may not include the interface unit 24 and the video signalprocessor 15, which are provided outside of the controller unit 120.

As described in the above-mentioned embodiments, each light emittingunit 40 is connected to each driver 30 of the driver unit 150. Asdescribed above, for example, one light emitting unit 40 includes theplurality of light emitting devices 42 connected in series. The powersource unit 60 supplies power to the controller unit 120 and the driverunit 150, and also supplies power to the light source unit 50 via thedriver unit 150.

(The respective drivers 30) of the driver unit 150 are connected to the(plurality of) positive supply lines 51 and the ground line 59. Eachlight emitting unit 40 is connected between the ground line 59 and eachpositive supply line 51. A potential higher than 0 volts of the groundline 59 is applied to each positive supply line 51. Each light emittingunit 40 is driven by a current generated by the voltage between theground line 59 and each positive supply line 51.

Here, if the controller unit 120 is also connected to a ground line(line 59 g), the following problem will occur. The return current fromthe light emitting units 40 flowing in the ground line 59 is a largecurrent, and this large current flows into the driver unit 150 and thecontroller unit 120. For example, if a current of 1 A to 2 A flows inone light emitting unit 40 and twenty light emitting units 40 areprovided, a large return current of 20 A to 40 A flows in the groundline 59.

For example, as shown in FIG. 9, the values of the currents flowing inthe (for example, four) light emitting units 40 will be referred to asIf1, If2, If3, and If4, respectively. The current flowing in the groundline 59 is the sum of those four current values, and the sum Ir isrepresented by Ir=If1+If2+If3+If4. Further, where Is is the currentflowing in the line 59 s of the ground line 59 toward the driver unit150 and where Ig is the current flowing in the line 59 g toward thecontroller unit 120, Ir=Ig+Is. Where the impedance of the controllerunit 120 is approximately the same as the impedance of the driver unit150, Ig=Ir. In other words, the half of Ir current flows into thecontroller unit 120.

Since the driver unit 150 is designed so as to treat a large current, alarge return current flowing into the driver unit 150 may not lead to aproblem. Meanwhile, if a large current flows into the controller unit120, as described above, a potential difference based on a resistancevalue, which is determined on the basis of a wiring pattern of theground line of the controller unit 120, is generated, and a common-modenoise is generated as a result.

Specifically, an electronic apparatus including the light source and thelight source control apparatus may include the conductive frame 70 thatsupports respective components including the light source unit 50, thecontroller unit 120 (controller board), and the like. In this case, theconductive frame 70 functions as an electric ground for the light sourcecontrol apparatus. Where there is the conductive frame 70, as describedabove, a potential difference is generated between the ground line ofthe controller unit 120 and the conductive frame 70, and a common-modenoise is generated as a result.

To solve such a problem, it is considered that the light source unit 50is insulated from the above-mentioned conductive frame 70. In theconductive frame 70 of FIG. 9, the dotted “cross” mark schematicallyshows that the light source unit 50 is insulated from the controllerunit 120 (conductive frame 70) as described above. Where the lightsource unit 50 is insulated from the conductive frame 70 in this way, itis possible to prevent the current Ig flowing into the controller unit120 through the conductive frame 70.

By the way, it is necessary to remove the light source unit 50 from anapparatus (for example, projector) in order to operate the light sourceunit 50 (for example, for maintenance, etc.). In order to remove thelight source unit 50, a cable that connects the driver unit 150 with thelight source unit 50 is disconnected. However, if the above-mentionedinsulation method as shown in the “cross” mark is employed, when thecable that connects the driver unit 150 with the light source unit 50 isdisconnected, the light source unit 50 electrically floats. Staticelectricity is generated in the light source unit 50, and the lightemitting devices 42 are thereby deteriorated, which is one of problems.

6. 1) Embodiment for Solving the Above-Mentioned Problem

FIG. 10 shows configurations of a light source unit and a light sourcecontrol apparatus for controlling the light source unit according to anembodiment for solving the above-mentioned problem. In this embodiment,the components the same as the component of the apparatus of theabove-mentioned comparative example (see FIG. 9) will be denoted by thesame reference signs, and description thereof will be omitted orsimplified.

The apparatus of this embodiment is different from the apparatus of theabove-mentioned comparative example mainly as follows. The light sourceunit 50A of this embodiment further includes the negative supply lines(second line) 52 in addition to the positive supply lines (first line)51 and the ground line (reference line) 59. Further, the second lightemitting units 40 b, i.e., at least one light emitting unit 40, areconnected between the ground line 59 and the negative supply lines 52.

The driver unit 150 is connected to the ground line 59, the positivesupply lines 51 and the negative supply lines 52. Specifically, thedriver unit 150 includes one or more first drivers 31. Each first driver31 generates a voltage between the reference potential (for example, 0V) and a potential higher than the reference potential, and causes eachfirst light emitting unit 40 a to drive. In other words, each firstdriver 31 is connected between each positive supply line 51 and theground line 59 (line 59 s).

Further, the driver unit 150 includes one or more second drivers 32.Each second driver 32 generates a voltage between the referencepotential (for example, 0 V) and a potential lower than the referencepotential, and drives each second light emitting unit 40 b. In otherwords, each second driver 32 is connected between each negative supplyline 52 and the ground line 59 (line 59 s).

In FIG. 10, for example, the values of the currents flowing in the twofirst light emitting units 40 a will be referred to as If1 and If2,respectively. Further, the values of the currents flowing in the twosecond light emitting units 40 b will be referred to as If3 and If4,respectively. The sum Ir of the current value flowing in the mergingpoint of the line 59 s connected to the driver unit 150 and the line 59g connected to the controller unit 120 out of the ground line 59 isIr=If1+If2−(If3+If4). Further, where Is is the current flowing in theline 59 s and where Ig is the current flowing in the line 59 g,Ir=Ig+Is.

Ir is obtained by subtracting If3 and If4 from the sum of If1 and If2.In this embodiment, since each light emitting unit 40 is driven byconstant current driving (including luminance adjusting range), If1,If2, If3, and If4 are substantially the same and Ir is thus an extremelysmall value. Therefore, since Ir=Ig+Is as described above, Ig is also anextremely small value.

As described above, in this embodiment, the return current flowing intothe controller unit 120 through the ground line 59 may be an extremelysmall value. As a result, generation of a potential difference based ona wiring pattern of the ground line of the controller unit 120 isreduced, and a common-mode noise is reduced. As a result, it is possibleto prevent malfunction of the controller unit 120 during signalprocessing may be prevented.

Further, in this embodiment, since the return current is extremelysmall, as described above, it is not necessary to insulate the lightsource unit 50 from the conductive frame 70, which functions as a groundbase. It is not necessary to disconnect a cable that connects the driverunit 150 with the light source unit 50 in order to operate the lightsource unit 50 (for example, for maintenance operation), and workabilityis increased. Further, the light source unit 50 does not electricallyfloat, and generation of static electricity in the light source unit 50is reduced. As a result, deterioration of the light emitting devices 42is reduced.

In this embodiment, since the potential of 0 V is used as the referencepotential, the design of the circuit of each driver may be simple. As amatter of course, a positive potential may be used as the referencepotential. For example, the high potential side may be 20 V, thereference potential may be 10 V, and the low potential side may be 0 V.In this case, the first light emitting unit 40 a may be connectedbetween the high potential side line (first line) and the reference line(reference potential side line), and the second light emitting unit 40 bmay be connected between the reference line and the low potential sideline (second line). In other words, the anode of the first lightemitting unit 40 a is connected to the high potential side line, and thecathode of the first light emitting unit 40 a is connected to thereference line. Further, the anode of the second light emitting unit 40b is connected to the reference line, and the cathode of the secondlight emitting unit 40 b is connected to the low potential side line.

According to this embodiment, the reference potential is set at aconstant value (typically, ground potential, i.e., 0 V), and each seconddriver 32 adjusts the potential of each negative supply line 52. As aresult, the above-mentioned driving value (current value) may beadjusted. In this way, since the potential lower than the referencepotential is adjusted, troubles of the second drivers 32 and the othercircuits are reduced and safety is increased, which are advantageouseffects. Further, in this case, each first driver 31 is configured toadjust the potential of the positive supply line 51 to thereby adjustthe driving value (current value).

As shown in FIG. 10, the light source control apparatus may include theresistor element Rg in the line 59 g and the resistor element Rs in theline 59 s. As a result, the return current is converted into thermalenergy, and therefore the value of the return current flowing into thecontroller unit 120 and the driver unit 150 may be reduced.

Note that only one of the resistor elements Rg and Rs may be provided.In this case, preferably, only the resistor element Rg is provided. Notethat the resistor elements Rg and Rs are not essential components.

6. 2) Another Embodiment for Solving the Above-Mentioned Problem

FIG. 11 shows configurations of a light source and a light sourcecontrol apparatus according to another embodiment for solving theabove-mentioned problem.

The apparatus of this embodiment is different from that of theabove-mentioned embodiment as follows. The apparatus of this embodimentincludes a switcher unit that switches connection targets of the firstlight emitting unit 40 a such that the anode of the first light emittingunit 40 a at the high potential side is connected to the ground line 59and the cathode of the first light emitting unit 40 a is connected tothe negative supply line 52. For example, the switcher unit includes thecontroller unit 120 and the switch groups S1 and S2.

The switch group S1 includes the four switches Q1 to Q4 connected to oneor more (or maybe all the) first light emitting units 40 a. Similarly,the switch group S2 includes the four switches Q1 to Q4 connected to oneor more (or maybe all the) second light emitting units 40 b. FIG. 11shows a configuration in which the first light emitting unit 40 aincludes one switch group, and the second light emitting unit 40 bincludes one switch group.

For example, semiconductor switches such as FET (Field EffectTransistor) are used as the switches Q1 to Q4. The controller unit 120controls on/off switching of the switches Q1 to Q4. Hereinafter, theswitch group S1 of the first light emitting unit 40 a will be described.

The switch Q1 is connected between the positive supply line 51 and theanode of the first light emitting unit 40 a (anode of the light emittingdevice 42 at an end). The switch Q2 is connected between the cathode ofthe first light emitting unit 40 a (cathode of the light emitting device42 at the opposite end) and the ground line 59.

The switch Q3 is connected to the anode of the first light emitting unit40 a in parallel with the switch Q1, and connected between the anode ofthe first light emitting unit 40 a and the ground line 59. The switch Q4is connected to the cathode of the first light emitting unit 40 a inparallel with the switch Q2, and connected between the cathode of thefirst light emitting unit 40 a and the ground line 59.

According to this configuration, the following operation is executable.For example, it is assumed that the light source unit 50 includes aplurality of (for example, ten) first light emitting units 40 a and aplurality of (for example, ten) second light emitting units 40 b. Inthis case, if even-number, for example, two, second light emitting units40 b are in trouble out of the ten second light emitting unit 40 b, thecontroller unit 120 detects that by using any method. Examples ofdetection methods include current detection, voltage detection, or lightemission illuminance detection.

Further, the controller unit 120 switches the switch group S1 such thatone first light emitting unit 40 a including the switch group S1functions as a light emitting unit at the low potential side, i.e.,functions as a second light emitting unit. Specifically, in the firstlight emitting unit 40 a, the switches Q1 and Q2 are turned off, and theswitches Q3 and Q4 are turned on. Then, nine light emitting units at thehigh potential side operate normally, and also nine light emitting unitsat the low potential side operate normally. As a result, the electricpower and illuminance of the positive side and the negative side of thelight source unit 50 are well balanced. As a result, even if some of thelight emitting units are in trouble, it is easy to control the lightsource unit 50, and generation of illuminance unevenness may beprevented.

For example, even if even-number first light emitting units 40 a are introuble, by switching the switch group S2 of the second light emittingunit 40 b in the similar way, the similar effect may be obtained.

Not limited to the purpose of making a good balance of the positive sideand the negative side, the on/off control of the switch groups may beperformed for other purposes. Examples of other purposes include toadjust the basic light emission amount from the light source unit 50(for example, in a case of using an apparatus always at a light amountthe half of the maximum light emission amount) and the like.

According to this embodiment, similar to the above-mentioned embodiment,the reference potential is set at a constant value (typically, groundpotential, i.e., 0 V), and each second driver 32 adjusts the potentialof each negative supply line 52. As a result, the above-mentioneddriving value (current value) may be adjusted. Further, in this case,each first driver 31 is configured to adjust the potential of thepositive supply line 51 to thereby adjust the driving value (currentvalue).

7. Embodiment 3

Next, Embodiment 3 will be described, which is different from theabove-mentioned 2. 2) Embodiment 1 (Example 1 of specific function) and2. 3) Embodiment 2 (Example 2 of specific function). The presentEmbodiment 3 is a modification example of the mode shown in FIG. 5including a plurality of driving regions (for example, function regionsof a plurality of straight lines). In other words, similar to Embodiment2, the present Embodiment 3 is also applied to a case in which theentire curve of a function is approximated in a plurality of linearregions.

FIG. 12 is a graph showing the relation between the driving current andthe light amount of Embodiment 3. A functions is shown. The functionincludes, as a plurality of function regions, for example, six linearregions from the oscillation threshold current I0 to the referencedriving current Ic.

Similar to the gist of the above-mentioned Formula 1.4,Iy=(Py−P _(n))/k _(n) +I _(n)  Formula 3.1n is an integer of 0 or more. In this embodiment, the reference drivingcurrent Ic is I₆, and the reference light amount Pc corresponding tothis Ic is P₆.

Similar to the gist of the above-mentioned Formula 1.1, inclinationk_(n) is represented by the following Formula 3.2.k _(n)=(P _(n+1) −P _(n))/(I _(n+1) −I _(n))  Formula 3.2Formula 3.1 is converted into the following Formula 3.3 on the basis ofFormula 3.2.Iy=[(I _(n+1) −I _(n))/(P _(n+1) −P _(n))](Py−P _(n))+I _(n)  Formula3.3In the example of FIG. 12, P₃≤Py≤P₄.

Each driver 30 obtains from the controller 20 or prestores the maximumvalue of n (in this embodiment, 6), I_(n), and P_(n), as knownparameters. For example, the controller 20 transmits those knownparameters to each driver 30 before adjusting the light amount (forexample, when powering on). Alternatively, each driver 30 prestoresfactory-configured known parameters.

Further, each driver 30 may obtain from the controller 20 or prestorethe calculation results of “(I_(n+1)−I_(n))/(P_(n+1)−P_(n))” of Formula3.3 of the respective linear regions. When adjusting the light amount,the controller 20 broadcasts the instruction value y (=Py/Pc) to therespective drivers 30. Each of the drivers 30 determines the n value onthe basis of y (Py corresponding to y) received from the controller 20to thereby determine the linear region to be applied to adjustment. Theneach of the drivers 30 adjusts the light amount on the basis of Formula3.3.

Note that each driver 30 may obtain the maximum value of n on the basisof I_(n) and P_(n)that the driver 30 stores. In other words, the driver30 is capable of calculating the maximum value of n on the basis of thenumber of I_(n) or P_(n). Further, since Ic=I₆ and Pc=P₆, the driver 30may store I₆ and P₆ as Ic and Pc.

8. To Generate Function of Driving Current and Light Amount

Next, a means for generating a function of a driving current and a lightamount easily when designing the light source control apparatus of thepresent technology will be described.

For example, as the plurality of light emitting units 40 (see FIG. 1,etc.), the N-number light emitting units 40 are driven at the samecurrent value, the light amount is measured under this situation, andthereby the function of the total light amount of the N-number lightemitting units 40 is generated. The total light amount of the N-numberlight emitting units 40 will be referred to as Psum. FIG. 13A is a graphshowing the relation between the driving current and the total lightamount Psum.

Psum is multiplied by 1/N to thereby calculate the average value of theN number. The light amount of each one light emitting unit 40 will bereferred to as Pone. In other words, the average light amount Pone willbe represented by the following formula.Pone=Psum/N  Formula 4.1

FIG. 13B is a graph showing the relation between the driving current andthe average light amount Pone. In each of the above-mentionedEmbodiments 1 to 3, each driver 30 is configured to use each function(function different depending on individual difference) when adjustingthe light amount. However, when Formula 4.1 is applied, the respectivedrivers 30 use the common function of FIG. 13B.

Each driver 30 is capable of adjusting the light amount by using thefunction of the driving current and the average light amount Pone on thebasis of, for example, the method of one of the Embodiments 1 to 3. Notethat the functions of FIG. 13A, B are the similar kind of the functionof FIG. 3, for example. However, as a matter of course, a functionsimilar to the function of FIG. 5 or 12 may be used.

As described above, it is possible to generate a function on the basisof the average light amount Pone easily, and it is possible to adjustthe total light amount by using the function with a high degree ofaccuracy.

The average light amount of each light emitting unit 40 (each driver 30)is described above. However, where there are the separate light sourceunits (light sources) 50 based on the wavelength bands as shown in FIG.7, the average light amount Pone of each light source 50 may be used. Inthis case, since there are the light sources 50R, 50G, and 50B of thedifferent wavelength bands, N is at least 3.

9. Timing of Changing Driving Current Value of Driver

For example, there is known a fact that, when each driver 30 (see FIG.1, etc.) changes the driving current of each light emitting unit 40 foradjusting the light amount, the time period until the driving current issettled is different from each other. In view of this, according to therespective drivers 30 of the light source control apparatus of thisembodiment, the timing of starting to switch the driving current of eachdriver 30 is different from each other.

Specifically, the delay time is set for the switch start timing of thedriving current of at least one of the respective drivers 30 such thatthe settlement completed timing is at the same time. Where thesettlement completed timing is at the same time, even if the functionsare different depending on the light emitting units 40 as describedabove, the luminance may be uniform, and especially the white balancemay be uniform (may not be deteriorated).

“The same time” may be substantially the same time as long as such anobject may be attained.

Basically, the start point of the delay time is designed in two ways.One example of the start point of the delay time is the timing at whicheach driver 30 receives a command to change the target current valuefrom the controller 20. The other example is the timing at which eachdriver 30 receives a synchronization signal, the synchronization signalbeing generated by the controller 20 in order to switch the drivingcurrent. The delay time is predetermined when designing the light sourcecontrol apparatus.

In the latter example (the other example), the controller 20 generatesthe above-mentioned change command, and then generates thesynchronization signal. FIG. 14A shows, as a comparative example, anexample in which the driving current is changed (decreased bypredetermined current value) to adjust the light amount where no delaytime is set. FIG. 14B shows, in this embodiment, an example in which thesettlement completed timing is approximately at the same time where thedelay time is set. In the examples of FIG. 14A and FIG. 14B, for abetter understanding, the synchronization signal (for example, pulsesignal) S for switching the driving current is the start point of thedelay time. Each driver 30 receives the change command or thesynchronization signal S broadcasted from the controller 20.

FIG. 14A shows, from the top in order, the synchronization signal S forswitching the driving current, the current waveform Ca of one lightemitting unit A, and the current waveform Cb of another light emittingunit B. The current waveform Ca of the light emitting unit A isdifferent from the current waveform Cb of the light emitting unit B inwhich the time period from receiving the synchronization signal S byeach driver to reaching each predetermined current value, i.e., thesettling time, is different from each other. The settling time t1 of thelight emitting unit A is shorter than the settling time t2 of the lightemitting unit B.

In view of this, according to this embodiment, as shown in FIG. 14B, inorder to make the settling time approximately the same, the delay timetd (=t2−t1) is set, which means that the settling time t2 of the lightemitting unit A is realized instead of the settling time t1. Forexample, where three or more light emitting units 40 are provided, inorder to make the settling times of the two or more other light emittingunits the same as the latest settling time, each delay time is set foreach of the two or more settling times.

The controller 20 transmits each delay time td as a known parameter toeach driver 30 before adjusting the light amount (for example, whenpowering on). Alternatively, each driver 30 prestores factory-configureddelay time td. alternatively, each driver 30 may prestore the time towhich the delay time is applied (for example, time t1+td). In this case,in principle, the time t2 is different for each driver 30 (for eachlight emitting unit 40).

By the way, it is assumed that, as the at least three light emittingunits 40, RGB three light emitting arrays are used as the light sources50. Typically, it is assumed that the light sources 50R, 50G, and 50B ofFIG. 7 are used as the light sources 50. The settling time of the lightsource 50R that generates red light is substantially the same as thesettling time of the light source 50B that generates blue light.However, the settling time of the light source 50G that generates greenlight is later (longer) than the settling time of the light sources 50Rand 50B. This embodiment has been made to solve this problem, and it ispossible to make the settling time the same and to keep the whitebalance uniform.

According to this embodiment, for example, a plurality of differentdelay times may be set depending on the change amount before and afterswitching a driving current (before and after determining drivingvalue). In other words, each driver 30 selectively uses one of aplurality of different switch start timings depending on its changeamount. For example, the delay time Ta [ms] may be set where theincreased amount is less than Iup [A], and the delay time Tb [ms] may beset where the increased amount is Iup [A] or more. Further, the delaytime Tc [ms] may be set where the decreased amount is less than Idown[A], and the delay Td [ms] may be set where the decreased amount isIdown [A] or more, for example. Alternatively, not only two levels asdescribed above but also three or more levels may be set for the changeamount.

Note that the present technology may employ the followingconfigurations.

(1)

A light source control apparatus, including:

-   a controller configured to transmit an instruction value for    adjusting a light amount of at least one light emitting unit; and-   a plurality of drivers, each of the plurality of drivers being    configured to obtain the transmitted instruction value, and to    determine, by using a function of a driving value for driving the    light emitting unit and the light amount, the function being each    set for the light emitting unit, the driving value of the light    emitting unit each on the basis of the instruction value.

(2)

The light source control apparatus according to the above-mentioned item(1), in which each driver of the plurality of drivers is configured touse, as the function, a function approximated by a straight line.

(3)

The light source control apparatus according to the above-mentioned item(1), in which each driver of the plurality of drivers is configured touse, as the function, a plurality of functions set corresponding to aplurality of driving regions, respectively.

(4)

The light source control apparatus according to the above-mentioned item(2), in which each driver of the plurality of drivers is configured touse, as the function approximated by a straight line, functionsapproximated by straight lines in a plurality of linear regions setcorresponding to a plurality of driving regions, respectively.

(5)

The light source control apparatus according to the above-mentioned item(2) or (4), in which

-   each driver of the plurality of drivers is configured to use the    function with known parameters, the known parameters including an    inclination of the straight line, a reference light amount, and a    reference driving value corresponding to the reference light amount.

(6)

The light source control apparatus according to the above-mentioned item(5), in which each driver of the plurality of drivers is configured toobtain from the controller or prestore a calculated value based on theinclination of the straight line and the reference light amount out ofthe known parameters.

(7)

The light source control apparatus according to any one of theabove-mentioned items (1) to (6), in which

-   the controller is configured to update the function on the basis of    a predetermined condition.

(8)

The light source control apparatus according to any one of theabove-mentioned items (1) to (7), in which

-   the controller is configured to broadcast the instruction value to    the plurality of drivers.

(9)

The light source control apparatus according to any one of theabove-mentioned items (1) to (8), in which

-   the plurality of drivers include-   a plurality of first wavelength band light-emitting drivers, each of    the plurality of first wavelength band light-emitting drivers being    configured to drive a plurality of light emitting units that emit    light having a first wavelength band out of the at least one light    emitting unit, and-   a plurality of second wavelength band light-emitting drivers, each    of the plurality of second wavelength band light-emitting drivers    being configured to drive a plurality of light emitting units that    emit light having a second wavelength band different from the first    wavelength band out of the at least one light emitting unit, and-   the controller is configured to transmit a first instruction value    to each of the plurality of first wavelength band light-emitting    drivers, and to transmit a second instruction value to each of the    plurality of first wavelength band light-emitting drivers.

(10)

The light source control apparatus according to any one of theabove-mentioned items (1) to (9), in which

-   the light emitting unit includes a first light emitting unit and a    second light emitting unit, and-   the plurality of drivers include-   a first driver configured to generate a voltage between a reference    potential of a reference line and a potential of a first line higher    than the reference potential, and to drive the first light emitting    unit connected between the reference line and the first line, the    first driver being connectable to the reference line and the first    line, and-   a second driver configured to generate a voltage between the    reference potential and a potential of a second line lower than the    reference potential, and to drive the second light emitting unit    connected between the reference line and the second line, the second    driver being connectable to the reference line and the second line.

(11)

The light source control apparatus according to the above-mentioned item(10), in which each of the first driver and the second driver isconfigured to use a potential of 0 volts as the reference potential.

(12)

The light source control apparatus according to the above-mentioned item(10) or (11), in which

-   a constant potential is set as the reference potential, and-   the second driver is configured to adjust a potential lower than the    reference potential to adjust the driving value.

(13)

The light source control apparatus according to the above-mentioned item(12), in which the first driver is configured to adjust a potentialhigher than the reference potential to adjust the driving value.

(14)

The light source control apparatus according to any one of theabove-mentioned items (10) to (13), further including:

-   a switcher unit that switches connection targets of the first light    emitting unit such that an anode of the first light emitting unit is    connected to the reference line and a cathode of the first light    emitting unit is connected to the second line.

(15)

The light source control apparatus according to any one of theabove-mentioned items (10) to (13), further including:

-   a switcher unit that switches connection targets of the second light    emitting unit such that a cathode of the second light emitting unit    is connected to the reference line and an anode of the second light    emitting unit is connected to the first line.

(16)

The light source control apparatus according to any one of theabove-mentioned items (10) to (15), further including:

-   a resistor element provided on at least one of a line connected to    the controller and a line connected to the plurality of drivers out    of the reference line.

(17)

The light source control apparatus according to the above-mentioned item(1), in which each driver of the plurality of drivers is configured touse, as the function, a function of an average light amount, the averagelight amount being obtained by dividing a total light amount of theplurality of light emitting units corresponding to driving values by thenumber of the light emitting units.

(18)

The light source control apparatus according to the above-mentioned item(1), in which each driver of the plurality of drivers is configured touse switch start timing of the driving value based on the instructionvalue, the switch start timings of the plurality of drivers beingdifferent from each other.

(19)

The light source control apparatus according to the above-mentioned item(18), in which delay time is set for the switch start timing of thedriving value of at least one of the respective drivers.

(20)

The light source control apparatus according to the above-mentioned item(19), in which each driver of the plurality of drivers is configured toselectively use the plurality of different switch start timingsdepending on a change amount of the driving values before and afterswitching the driving value.

(21)

A light source control method, including:

-   transmitting, by a controller, an instruction value for adjusting a    light amount of at least one light emitting unit;-   obtaining, by each of a plurality of drivers, the transmitted    instruction value; and-   determining, by each of the plurality of drivers, by using a    function of a driving value for driving the light emitting unit and    the light amount, the function being each set for the light emitting    unit, the driving value of the light emitting unit each on the basis    of the instruction value.

(22)

The light source control apparatus, including:

-   a first driver configured to generate a voltage between a reference    potential of a reference line and a potential of a first line higher    than the reference potential, and to thereby drive the first light    emitting unit connected between the reference line and the first    line, the first driver being connectable to the reference line and    the first line;-   a second driver configured to generate a voltage between the    reference potential and a potential of a second line lower than the    reference potential, and to thereby drive the second light emitting    unit connected between the reference line and the second line, the    second driver being connectable to the reference line and the second    line; and-   a controller unit connectable to the reference line, the first    driver, and the second driver, the controller unit being configured    to control the first driver and the second driver.

(23)

The light source control apparatus according to the above-mentioned item(22), in which each of the first driver and the second driver isconfigured to use a potential of 0 volts as the reference potential.

(24)

The light source control apparatus according to the above-mentioned item(22) or (23), in which

-   a constant potential is set as the reference potential, and-   the second driver is configured to adjust a potential lower than the    reference potential to adjust the driving value.

(25)

The light source control apparatus according to the above-mentioned item(24), in which the first driver is configured to adjust a potentialhigher than the reference potential to adjust the driving value.

(26)

The light source control apparatus according to any one of theabove-mentioned items (22) to (25), further including:

-   a switcher unit that switches connection targets of the first light    emitting unit such that an anode of the first light emitting unit is    connected to the reference line and a cathode of the first light    emitting unit is connected to the second line.

(27)

The light source control apparatus according to any one of theabove-mentioned items (22) to (25), further including:

-   a switcher unit that switches connection targets of the second light    emitting unit such that a cathode of the second light emitting unit    is connected to the reference line and an anode of the second light    emitting unit is connected to the first line.

(28)

The light source control apparatus according to any one of theabove-mentioned items (22) to (27), further including:

-   a resistor element provided on at least one of a line connected to    the controller and a line connected to the plurality of drivers out    of the reference line.

(29)

A driver unit, including:

-   a first driver configured to generate a voltage between a reference    potential of a reference line and a potential of a first line higher    than the reference potential, and to drive the first light emitting    unit connected between the reference line and the first line, the    first driver being connectable to the reference line and the first    line; and-   a second driver configured to generate a voltage between the    reference potential and a potential of a second line lower than the    reference potential, and to drive the second light emitting unit    connected between the reference line and the second line, the second    driver being connectable to the reference line and the second line.

(30)

A light source unit, including:

-   a first light emitting unit connected between a reference line and a    first line, the first light emitting unit being driven by a current    generated by a voltage between a reference potential of the    reference line and a potential of the first line higher than the    reference potential; and-   a second light emitting unit connected between the reference line    and a second line, the second light emitting unit being driven by a    current generated by a voltage between the reference potential of    the reference line and a potential of the second line lower than the    reference potential.

(31)

A projector, including:

-   a plurality of light emitting units;-   a light modulation device that modulates light from the plurality of    light emitting units;-   a projection optical system that projects modulated light obtained    by modulating the light by the light modulation device;-   a controller configured to transmit an instruction value for    adjusting a light amount of at least one light emitting unit; and-   a plurality of drivers, each of the plurality of drivers being    configured to obtain the transmitted instruction value, and to    determine, by using a function of a driving value for driving the    light emitting unit and the light amount, the function being each    set for the light emitting unit, the driving value of the light    emitting unit each on the basis of the instruction value.

(32)

The projector according to the above-mentioned item (31), in which

-   the plurality of light emitting units include-   a first light emitting unit connected between a reference line and a    first line, and-   a second light emitting unit connected between the reference line    and a second line, and-   the plurality of drivers include-   a first driver configured to generate a voltage between a reference    potential of the reference line and a potential of the first line    higher than the reference potential, and to drive the first light    emitting unit, the first driver being connected to the reference    line and the first line, and-   a second driver configured to generate a voltage between the    reference potential and a potential of a second line lower than the    reference potential, and to drive the second light emitting unit,    the second driver being connected to the reference line and the    second line.

(33)

A projector, including:

-   a plurality of light emitting units including a first light emitting    unit connected between a reference line and a first line, and a    second light emitting unit connected between the reference line and    a second line;-   a light modulation device that modulates light from the plurality of    light emitting units;-   a projection optical system that projects modulated light obtained    by modulating the light by the light modulation device;-   a driver unit including a first driver configured to generate a    voltage between a reference potential of the reference line and a    potential of the first line higher than the reference potential, and    to drive the first light emitting unit, the first driver being    connected to the reference line and the first line, and a second    driver configured to generate a voltage between the reference    potential and a potential of a second line lower than the reference    potential, and to drive the second light emitting unit, the second    driver being connected to the reference line and the second line;    and-   a controller unit connectable to the reference line, the first    driver, and the second driver, the controller unit being configured    to control the first driver and the second driver.

REFERENCE SIGNS LIST

-   20 controller-   30 driver-   31 first driver-   32 second driver-   40 light emitting unit-   40 a first light emitting unit-   40 b second light emitting unit-   42 light emitting device-   50, 50R, 50G, 50B, 50A, 50B light source (light source unit)-   51 positive supply line-   52 negative supply line-   59 ground line-   101, 102 light source control apparatus-   120 controller unit-   150 driver unit-   210 light modulation device-   500 projector

What is claimed is:
 1. A light source control apparatus, comprising: acontroller configured to transmit an instruction value to adjust a lightamount of at least one light emitting unit; and a plurality of drivers,wherein each driver of the plurality of drivers is configured to: obtainthe transmitted instruction value; determine a driving value of eachlight emitting unit of the at least one light emitting unit, based onthe instruction value and a function of the driving value, wherein thefunction drives a corresponding light emitting unit of the at least onelight emitting unit and the light amount of the at least one lightemitting unit, and the function is set for each light emitting unit ofthe at least one light emitting unit; and use, as the function, aplurality of functions set corresponding to a plurality of drivingregions, respectively.
 2. The light source control apparatus accordingto claim 1, wherein each driver of the plurality of drivers is furtherconfigured to use the function approximated by a straight line.
 3. Thelight source control apparatus according to claim 2, wherein each driverof the plurality of drivers is further configured to use, as thefunction approximated by the straight line, a plurality of functionsapproximated by straight lines in a plurality of linear regions setcorresponding to the plurality of driving regions, respectively.
 4. Thelight source control apparatus according to claim 2, wherein each driverof the plurality of drivers is further configured to use the functionwith parameters, and the parameters include an inclination of thestraight line, a reference light amount, and a reference driving valuecorresponding to the reference light amount.
 5. The light source controlapparatus according to claim 4, wherein each driver of the plurality ofdrivers is further configured to one of obtain from the controller orstore a calculated value, based on the inclination of the straight lineand the reference light amount.
 6. The light source control apparatusaccording to claim 1, wherein each driver of the plurality of drivers isfurther configured to use, as the function, a function of an averagelight amount, and the average light amount is obtained based on adivision of a total light amount of the at least one light emitting unitcorresponding to driving values by a number of light emitting units. 7.A light source control apparatus, comprising: a controller; and aplurality of drivers, wherein the controller is configured to: transmitan instruction value to adjust a light amount of at least one lightemitting unit; and broadcast the instruction value to the plurality ofdrivers, wherein each driver of the plurality of drivers is configuredto: obtain the transmitted instruction value; and determine a drivingvalue of each light emitting unit of the at least one light emittingunit, based on the instruction value and a function of the drivingvalue, wherein the function drives a corresponding light emitting unitof the at least one light emitting unit and the light amount of the atleast one light emitting unit, and the function is set for each lightemitting unit of the at least one light emitting unit.
 8. A light sourcecontrol apparatus, comprising: a controller configured to transmit aninstruction value to adjust a light amount of at least one lightemitting unit; a plurality of drivers, wherein each driver of theplurality of drivers is configured to: obtain the transmittedinstruction value; determine a driving value of each light emitting unitof the at least one light emitting unit, based on the instruction valueand a function of the driving value, wherein the function drives acorresponding light emitting unit of the at least one light emittingunit and the light amount of the at least one light emitting unit, andthe function is set for each light emitting unit of the at least onelight emitting unit; a first light emitting unit; and a second lightemitting unit, wherein the plurality of drivers include: a first driverconfigured to: generate a first voltage between a reference potential ofa reference line and a first potential of a first line higher than thereference potential, and drive the first light emitting unit connectedbetween the reference line and the first line, wherein the first driveris connectable to the reference line and the first line, and a seconddriver configured to: generate a second voltage between the referencepotential and a second potential of a second line lower than thereference potential, and drive the second light emitting unit connectedbetween the reference line and the second line, wherein the seconddriver is connectable to the reference line and the second line.
 9. Thelight source control apparatus according to claim 8, wherein the firstdriver and the second driver are further configured to use a thirdpotential of 0 volts as the reference potential.
 10. The light sourcecontrol apparatus according to claim 8, wherein the second driver isfurther configured to adjust a third potential lower than the referencepotential to adjust the driving value, and a constant potential is setas the reference potential.
 11. The light source control apparatusaccording to claim 10, wherein the first driver is further configured toadjust the second potential higher than the reference potential toadjust the driving value.
 12. The light source control apparatusaccording to claim 8, further comprising a switcher unit configured toswitch connection targets of the first light emitting unit such that ananode of the first light emitting unit is connected to the referenceline and a cathode of the first light emitting unit is connected to thesecond line.
 13. The light source control apparatus according to claim8, further comprising a switcher unit configured to switch connectiontargets of the second light emitting unit such that a cathode of thesecond light emitting unit is connected to the reference line and ananode of the second light emitting unit is connected to the first line.14. The light source control apparatus according to claim 8, furthercomprising a resistor element on at least one of the first lineconnected to the controller or the second line connected to theplurality of drivers, and wherein the reference line comprises the firstline and the second line.